Number of iterations for inverse modeling of parameters. In each iteration the total time history as defined by the control_timestep records will be applied. Moreover, it will be applied for the current estimate of the parameters and once for each parameter varied a bit (see inverse_variation); in this way, the sensitivity of the target data with respect to the parameters is determined. At the end of the iteration, these sensitivities are used to determine new estimates for the parameters. In case of problems consider using inverse_parameter_step. See also: inverse_target.